Method and means for removing carbon deposits from cylinders



Patented Dec. 30, 1930 UNITED STATES PATENT oFFicE THOMA MIDGLEY, JR, AND CARROLL ALONZO HOCH'WALT, OF DAYTON, OHIO, AS-

SIGNORS 'IO GENERAL MOTORS RESEARCH CORPORATION, 013 DETROIT, MICHIGAN, A

CORPORATTON OF DELAWARE METHOD AND MEANS FOR REMOVING CARBON DEPOSITSIROM CYLINDERS No Drawing.

This invention relates to the removal of carbon-like deposits from the walls of the combustion chamber of an internal combustion engine. The principal object of the present invention is to provide a method and means for dissolving and softening the tarrylike binder which holds dust and carbon particles to the metal, and removing these particles.

This application is a continuation in part of our application Serial No. 663,478 filed September 18th, 1923.

Many substances have a small solvent action on the tarry-binder when the binder is relatively cool and are practically inefiective at higher temperatures because the substance is vaporized. In our method we make use of relatively high temperatures to accelerate the action of the solvent and employ as the primary solvent ahigh boiling oil soluble alkaline material such as a high boiling organic compound which is a solvent for varnish and maintain this solvent in liquid phase in contact with the hot carbon. This combination of high temperature and solvent power readily dissolves and softens the tarry-like part of the deposit.

. This action may be hastened by employing with this primary solvent, a secondary solvent, also of the type employed for removing varnish, but which is of quite a fluid character, and which preferably has a lower boiling point than the primary solvent.

This secondary solvent not only acts to soften or dissolve the'binder, but also accelerates the action of the primary solvent by assisting penetration into the pores of the carbon-like mass and by keeping the solution agitated through local convection or bubbling; Where oil is present on or in the carbon deposit, the secondary solvent cuts the oil.

By way of example, we may form a mixture consisting by volume of one part aniline, one part ethyl alcohol, one part benzol, and one part naphthalene. A layer of this mix- Application filed February 2, 1926. Serial No. 85,579.

ture is spread over a metal surface coated with a carbon deposit, such as a piston head which is maintained at a temperature above 150 F. and preferably in the neighborhood of but below the boiling point of aniline. The nearer the temperature to the boiling point of aniline the more rapid the solvent action. After the solvent has been left in contact with the hot carbon for a period of about two hours or more, the carbon deposit is wiped off. Or from 20 to 40 c. c. of the mixture is placed in a hot cylinder of an engine,

and the engine is then left idle for several hours. Later when the engine is started the loosened carbon is blown out the exhaust. Optimum temperature conditions in a water cooled engine are just below the boiling point of water.

The process may be varied by changing the proportions given, by employing only the primary solvent or only the primary solvent and the secondary solvent, which latter, in the example given, is benzol and alcohol, and by employing other solvents. The primary solvent may be a high boiling primary aromatic amine such as toluidine, Xylidine, cumidine, or a high boiling secondary aromatic amine, including monomethyl aniline and its homologues, monomethyl toluidine and its homologues, monomethyl Xylidine and its homologues, or the high boiling tertiary heterocyclic amines, including pyridine, quinoline and its homologues, and the high boiling tertiary aromatic amines including dimethyl aniline and its homologues, dimethyl toluidine and its homologues, and dimethyl Xylidine and its homologues. The trivalent compounds g ve excellent results and more especially the secondary and tertiary aromatic amines called alkyl or aryl anilines, toluidines, xylidines, etc., which include chemicals named in the classes above.

It appears that naphthaline also assists the solvent action and this may be employed as time for loosening the carbon, especially where the carbon deposit is relatively thick.

We claim:

1. The process of cleaning a carbon deposit from a metal surface of a combustion chamber of an internal combustion engine, which comprises heating the metal to above 150 F., applying to the carbon deposit a high boiling oil soluble alkaline organic material, until the tarry-binder in the deposit issoftfened, and removing the carbon from the surace.

2. The process of cleaning a carbon deposit from the combustion chamber of an internal combustion engine which comprises heating the combustion chamber to the neighborhood of the boiling point of water, applying to the carbon deposit a high boiling organic compound which removes varnish, until the tarry-binder in the deposit is softened, and removing the carbon deposit.

3. The process of cleaning a carbon deposit from a metal surface of a combustion chamber, which comprises heating the metal to above 150 F., applying to the carbon deposit a mixture of a high boiling organic compound which removes varnish and a lower boiling varnish remover, until the tarry-binder in the deposit is softened, and removing the carbon deposit.

4. The process of cleaning a carbon deposit from a metal surface of a combustion chamber, which comprises heating the metal to above 150 F, applying to the carbon.

deposit amixture of a high boiling organic compound which removes varnish, alcohol and benzol, until the tarry-binder in the deposit is softened, and removing the carbon from the surface.

5. The process of cleaning a carbon deposit from a metal surface of a combustion chamber, which comprises heating the surface to above 150 F., applying to the carbon deposit a mixture of an line, alcohol and benzol, until the tarry-binder in the deposit is softened, and removing the carbon from the surface.

6. A composition of matter for removing carbon comprising a high boiling varnish remover and a lower boiling varnish remover.

7. A composition of matter for removing carbon comprising a high boiling varnish remover, alcohol and benzol.

, 8. A composition of matter for removing carbon comprising aniline and a lower boiling varnish remover.

9. A composition of matter for removing carbon. comprising aniline, a lower boiling varnish remover, and naphthaline.

10. A composition of matter for removinq carbon comprising aniline, alcohol, ben- 2 ol, and naphthaline.

11. The process of cleaning a carbon deposit from a metal surface of a combustion chamber of an internal combustion engine, which comprises heating the metal, applying 

